Abstract

A photovoltaic electrochromic window was developed by combining electrochromic glass with photovoltaic window. The photovoltaic electrochromic window is installed with a solar cell layer photovoltaic module on the surface, which is connected with the inner electrochromic glass layer chromic module. It can not only be self-sufficient to achieve the purpose of energy conservation, but also can use the energy generated by the photovoltaic module to freely control the working condition of the color-changing module to achieve the regulation of the indoor lighting environment. In order to study the system performance of the new designed photovoltaic electrochromic windows under different working conditions, a test platform for the comprehensive performance of power generation and lighting was established. According to the test results, it has been shown that PV electricity supplied for color window change can be satisfied with the discoloration modules needed. Under the fading condition, the transparent transmission rate is 13%, and the transmittance under shading condition is much smaller. It means that completely shading mode have a better control on the indoor lighting environment in sunny day compared with transparent fading. In order to deeply analyze the influence of photovoltaic electrochromic windows on indoor lighting environment, a comparative test was conducted between ordinary windows and photovoltaic electrochromic windows under various climatic conditions, and the test data was analyzed through the dynamic evaluation index of lighting environment, including the percentage of total natural lighting time DA and effective lighting illumination UDI. The comparison test results showed that photovoltaic electrochromic windows, compared with ordinary windows, can create a better lighting environment in sunny days under different working conditions. The coupling of photovoltaic modules and electrochromic modules enables photovoltaic electrochromic windows to regulate indoor light environment more flexibly.

Abstract

This paper dealt with a series of numerical investigations on a new porous cooling channel applied to PV/T systems in order to improve the insufficient heat transfer in the conventional channel. The proposed porous cooling channel based on field synergy theory had a higher overall heat transfer coefficient, which enhanced the total efficiency of the PV/T system. The numerical model was validated with experimental data. The results showed that the total efficiency of the PV/T system with the new cooling channel was 4.17% higher than the conventional one at a solar radiation of 1000 W/m2 and an inlet mass flow rate of 0.01 kg/s. In addition, as the solar radiation increased from 300 to 1200 W/m2, the total efficiency of the new PV/T system dropped by 5.07%, which included reductions in both the electrical and thermal efficiency. In addition, the total efficiency of the PV/T system with the new cooling channel was 4% higher than that of the conventional cooling channel.

Abstract

Bifacial photovoltaic (bPV) technology can output more power than conventional mono-facial PV (mPV) technology by absorbing sunlight from both sides, which attracts increasing attention and its market share is predicted from 15% in 2019 to 70% in 2030. However, there are still no unified plans on what type of the mPV modules should be taken as reference. Therefore, in this study, the similar structure (double glass) of bPV and mPV modules are employed not only validate the previous numerical simulation results, but also to estimate the bPV performance. Furthermore, the daily bPV and mPV electrical and thermal performance is measured and compared under the same conditions. Results show that the bPV modules obviously outperform the mPV modules, and the average bifacial gain can be up to 17.33%. At the same time, the bPV module is cooler than the mPV due to the absence of the back surface field. In addition, some important factors on the bPV performance are discussed by simulation. Results indicates that it is better to install a bPV module with high albedo, elevation, tracking technology at an optimum tilt angle to obtain high power output.

Abstract

This paper presents a game theory-based modeling framework for government subsidy optimization and renewable multi-energy system (MES) design. The government offers subsidy for renewable technologies, while consumers return rational response to government subsidy on deploying renewable technologies in their respective MES. The game theory-based subsidy optimization and MES design is first formulated as a mixed-integer bilevel nonlinear programming problem and then transformed into a single level mixed-integer linear programing problem using Karush-Kuhn-Tucker conditions and linearization strategies. The results show that the government needs to provide a total subsidy of 3.86 million USD in order to achieve a renewable penetration of 60% in a small urban city composed of four towns. With government subsidy, the total net present costs for the four towns are 8.24, 6.7, 8.32, and 8.93 million USD, respectively.

Abstract

Carbon label is an important tool for countries to achieve green economy in the context of global climate change. Since the public is the end consumer of carbon-labeled products, understanding their attitudes towards carbon label is crucial for the future development of carbon labeling system. Under this background, we conduct a survey on consumers’ perception of carbon-labeled electrical and electronic products (CEP) in Chinese first-tier cities. Consumers’ premium willingness to pay for CEP and its influencing factors are explored. After correcting the possible bias by sample selection model, we find that 85.97% of respondents are willing to pay more for carbon-labeled products. Besides, Males, respondents who are younger or richer, or with underaged children at home are more willing to pay a premium for carbon-labeled products. The degree of trust and understanding of carbon label also has a positive impact on the premium WTP. As for the specific value of premium WTP, an additional 7.85% of the original price for CEP is willing to be paid. The above findings can provide targeted reference for policymakers in pricing carbon-labeled products, and also yield effective policy recommendations for the future development of carbon label system.

Abstract

It is difficult to ensure the completeness of information obtained in the market competition, so the study of optimal scheduling of multi-energy hub systems with incomplete information plays an important role in the stability and economic operation of the system. However, the energy hubs in the multi-energy hub systems restricted each other, and the optimal modeling with integrated demand response was affected by user behavior and market information asymmetry. Therefore, in view of the competition among energy hubs under the dynamic electricity price mechanism, incomplete information game was adopted to solve the optimization scheduling problem of multi-energy hubs under the condition of incomplete information. According to the difference of the behavior characteristics of users participating in the comprehensive demand response, the interruptible load type participating in the demand response was modeled as discrete random variables by introducing the user load interruption willingness factor. Furthermore, a multi-energy hub systems optimal scheduling model with incomplete information demand response selection was established and its Bayesian Nash equilibrium was given. Then the examples were given to verify the validity of the model and the method. The results show that the comprehensive demand response and incomplete information have an important impact on the dispatching decision of multi energy hub system. When making decision, it is necessary to consider all kinds of situations that may be formed due to incomplete information.

Abstract

The cold-start performance of proton exchange membrane fuel cells is of great significance to their real-world application. Few experimental studies have investigated the effects of contact pressure distribution on the cold-start performance of fuel cells. In this study, the effects of the changes in the contact pressure distribution between the cathode catalytic layer and the micro-porous layer were experimentally evaluated by varying the channel width of the cathode electrode plate. The output voltage and high-frequency impedance measurements obtained during the cold start of the fuel cell demonstrated that the contact pressure distribution affected the cold-start performance and the effects varied with the temperature. These results indicate that the channel configuration and bolt tightening torque could be manipulated to achieve the best performance under the intended operating conditions.

Abstract

The power output of a photovoltaic (PV) module depends on the specific climate conditions of each location and on the spectral response of each technology. The impact of solar radiation duration?, temperature, humidity, dust can strongly affect the energy production of a PV system. Chengdu, in Southwest of China (Latitude 30.34o North, Longitude 105.55o East), with a typical low irradiation weather condition, was considered not feasible to install PV systems. However, the performance of PV module of different technologies in Chengdu is seldom reported. This paper presents an energy performance analysis of six different PV modules under outdoor conditions at Sichuan University in Chengdu. For this purpose, by using p-Mono crystalline, p-Multi crystalline, amorphous silicon, CdTe, CuInGaSe and bifacial modules, six 1 kWp on-grid photovoltaic power systems (PPS) were installed on the rooftop of the Institute of New Energy and Low-Carbon Technology at Sichuan University. These PPSs were monitored from January to December, 2019. It was found that the p-Mono crystalline PV module showed the most excellent energy output of 830.9kWh, while the CuInGaSe only produced 758.1 kWh. The energy output order is p-Mono > amorphous silicon > CdTe > p-Multi > bifacial > CuInGaSe. On total 33 sunny days in 2019, amorphous silicon module performs best, followed by p-Mono and CdTe. However, on the cloudy and rainy days, power generation of p-Mono is the most, then p-Multi and bifacial module, while CuInGaSe generates the minimum. It can be found that PV panels with p-Mono modules have the best power generation capacity in Chengdu, for the good performance both in sunny days and in cloudy days. The second component is amorphous silicon module, which also have good power generation capacity in sunny days and cloudy days. CdTe is suitable for sunny days, while p-Multi and bifacial have more advantages and stability in cloudy days. CuInGaSe has the worst power generation capacity, which is backward in all kinds of weather with poorest stability, so it is not suitable to be installed in low irradiated area, like Chengdu. This work provides a precise evaluation of outdoor power generation capacity for different PV modules under low irradiation weather conditions. The results can provide important indications for the PV users and suppliers to install proper solar modules at areas with similar climate conditions as that of Chengdu.

Abstract

Accurate wind turbine power curves lay solid foundation for wind turbine performance evaluation and wind power forecasting, and then serve the planning and operating a low carbon energy system including renewables and electric vehicles. In order to improve the model accuracy, this paper presents the concept of quantile power curve and a quantile loss function based neural network algorithm, for establishing the proposed quantile power curve model. Based on the operational data of three wind turbines in a wind farm in China, a case study is carried out to validate the proposed model. The results show that the proposed quantile power curve model has good reliability.

Abstract

With the development of China’s urbanization process, steel plants are gradually surrounded by cities. The coexistence of steel industries and cities has become inevitable. This paper presents a concept of upgrading and using municipal combustible waste (MCW) and in the ironmaking process as fuel. Blast furnace (BF) injection of MCW can reduce the environmental hazards of the MCW disordered treatment, and it can also reduce the consumption of fossil fuels in ironmaking. However, the low energy density, high content of harmful elements and difficulties in grindability and injection limit its application in BF injection. This research innovatively proposed a new technical route that uses hydrothermal carbonization technology (HTC) to treat MOW and applies the prepared hydrochar to BF injection. The research results showed that the energy density of hydrochar is significantly increased, the content of harmful elements is greatly reduced, and the grindability is significantly improved. Meanwhile, compared with the bituminous coal, the hydrochar has better combustion performance and can be used as an alternative fuel for BF injection. It can foresee that the steel plant may facilitate on building up a low carbon city by valorizing and using MCW in the ironmaking process for the substitution of fossil fuels.